The Power in Potassium

Illustration: Gail Anderson and Joe Newton

This stealth nutrient may serve as an "antidote" to sodium. Getting more is easy—if you know where to find it. Sidney Fry, MS, RD

June 20, 2012

It was no surprise that the 2010 Dietary Guidelines for Americans came down hard on our salt habit: Less than 2,300mg a day is recommended for healthy adults, and 1,500mg for those who are older, African-American, or hypertensive—about half the U.S. population. Yet, average consumption is in the 3,400mg zone, and salt is blamed for hypertension and heart disease. Under the guidelines, pretty much everyone is supposed to cut back, and some of us need to cut back a lot. That much of a shift in the American salt habit seems like a long shot, however, which is why more and more research is paying close attention to potassium, a close mineral cousin to sodium—one that may counteract salt's role in disease.

"Potassium can help neutralize sodium's heart-damaging effects," says Elena Kuklina, MD, PhD, author of a study published in the Archives of Internal Medicine last year. Her findings, that an out-of-balance sodium-to-potassium ratio may increase the risk of heart disease (as opposed to a simple problem of too much salt), joins a growing body of research that shows how potassium can help lower the risk of heart attack and stroke. Those who ate a lot of salt and very little potassium were more than twice as likely to die from cardiovascular-related events than those who ate equal amounts of both nutrients. Potassium relaxes blood vessel walls and helps regulate the body's fluid balance, so the more you have, the better your body is able to deal with (that is, better able to excrete) excess sodium. It's not necessarily a get-out-of-jail-free card, but it's something anyone concerned about sodium needs to pay attention to.

Problem is, American consumption of potassium is low: 2,500mg per day, far beneath the 4,700mg recommended. Taking a potassium pill probably isn't the answer because the interaction between salt and potassium in the diet is not fully understood. In my book, the focus should not be on supplements but on diet: Whole foods, with their complex combinations of nutrients and fiber, are a better, not to mention tastier, bet. And there are plenty of potassium-rich foods out there; they're just not promoted as such. Potassium could benefit from a PR campaign.

Most people's knowledge of potassium-rich foods begins and ends with bananas, which at 500mg are certainly an excellent source. But so are other whole foods—fruits and 100% fruit juices, melons, green leafy vegetables, beans, potatoes, seafood, and dairy. Most of these foods, however, don't have labels, and even if they do, potassium is not one of the nutrients mandated by labeling laws. I'd like to see more complete nutrition labels on packaged foods, as well as simple in-store displays that list nutrition highlights for fresh food. (I can also imagine smart-phone apps that can scan both labels and fresh foods for nutrition data, then build a healthy shopping list.)

According to a 2011 Swedish analysis of 10 studies, for every additional 1,000mg per day of potassium added to the diet, risk of stroke decreased by 11%. A thousand milligrams may seem like a lot, but consider the following simple swaps. Trade a cup of orange juice for that second cup of morning coffee and you've just upped your potassium intake by 500mg. Swap a cup of nonfat yogurt for an afternoon vending-machine raid, and you tack 600mg more onto your daily total. Yes, some swaps involve added calories, but others save calories (not to mention fat and salt), so the net effect can be positive.

Despite their interest in the balancing role of potassium, many experts are wary of taking the focus off salt. Even as you up your potassium intake, it's wise to continue to use a light hand with the saltshaker and with sodium-rich foods. Note the per-serving sodium counts on packaged snacks, and steer clear of anything containing more than 250mg. Choose lower-sodium packaged foods for cooking: Lower-sodium canned beans, for example, have the same 600mg potassium as their saltier counterparts but save you 350mg per half cup on the sodium side of the ledger.

Enjoy fish, seafood, and dairy, and pair them with fresh fruit and vegetable options that are naturally low in sodium, like a summer peach salsa (another potassium all-star). By eating more whole foods, a shift in the balance between sodium and potassium will begin to occur naturally, and you'll put your body's built-in cardiovascular-disease-prevention abilities to work.

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